"A white Nissan Altima was headed north and had no time to stop," said Sgt. Gloria Tellez of CHP's Napa office. The Nissan hit the motorcycle, and a female passenger was ejected 50 to 60 feet, landing in a ditch alongside northbound Arnold Drive.

The woman was seriously injured and was airlifted to Queen of the Valley Hospital in Napa, according to an official on the scene.

A man who was driving the motorcycle died at the scene, Tellez said. He has been identified, but his name was not released pending notification of his next of kin.

"As of right now, we are still investigating who is at fault and whether alcohol was involved," said a CHP officer who declined to be identified.